Microfluidic dispenser device for delivering inhalable substances

ABSTRACT

A microfluidic dispenser device of inhalable substances includes a casing, housed in which are a driving circuit and a microfluidic cartridge having a tank that contains a liquid to be delivered. The microfluidic cartridge is provided with at least one nebulizer controlled by the driving device. The nebulizer includes: a substrate; a plurality of chambers formed on the substrate and fluidically coupled to the tank for receiving the liquid to be delivered; and a plurality of heaters, which are formed on the substrate in positions corresponding to respective chambers, are thermally coupled to the respective chambers and are separated from the respective chambers by an insulating layer, and are controlled by the driving device. Each chamber is fluidically connected with the outside by at least one respective nozzle.

BACKGROUND Technical Field

The present disclosure relates to a microfluidic dispenser device fordelivering inhalable substances.

Description of the Related Art

As is known, the need to control precisely delivery of inhalablesubstances, both for therapeutic purposes and for the production ofnon-medical devices, such as the so-called electronic cigarettes, hasled to the development of miniaturized delivering devices that are easyto use.

A dispenser device of inhalable substances of a known type normallycomprises a tank, which contains a fluid with the substances to bedelivered in solution, and at least one delivery chamber, provided withejector nozzles and supplied by the tank. An actuator housed in thechamber driven by a control device causes expulsion of a controlledamount of fluid.

Currently, in particular in electronic cigarettes, actuators of aresistive or inductive type are mainly used.

In resistive actuators, a resistive electrode is placed within thechamber and is wound, in contact, around a spongy cylindrical body, alsoreferred to as “wick”, which is generally made of glass fiber. Theelectrode traversed by current heats the fluid to be delivered up toboiling point, and the formation of bubbles causes expulsion ofcorresponding volumes of fluid to be delivered. Control of delivery isgenerally based upon flowmeters that detect the flow rate of fluidcoming out of the chamber. Delivery devices of this sort suffer fromcertain limitations. In the first place, the electrode is directly incontact with the fluid to be delivered, and this may lead to release ofundesirable and potentially harmful substances. Moreover, the entirevolume of fluid present in the chamber is brought to boiling point andhence reaches rather high temperatures. Such a condition may triggerreactions in the fluid that alter the substances to be delivered. If thesubstances to be delivered are drugs, the reactions may render theactive principles inefficacious. If, instead, the device deliverssurrogates of smoke, the organoleptic characteristics may be degraded.In the worst scenarios, the reactions due to the high temperature mayproduce harmful substances that are inhaled to the detriment of theuser. A further limit of known devices is the low precision incontrolling the doses of inhalable substances delivered.

In actuators of an inductive type, a coil is wound around the wick, at adistance. The coil traversed by current remains relatively cold, butgenerates a magnetic field that heats the spongy body and the liquiduntil it causes expulsion of the latter. Actuators of this type do notpresent problems linked to the release of substances from the coil(which is not in contact with the liquid) and to the excessive heating,but are costly and not suited to being integrated in disposablecartridges, as would be preferable.

BRIEF SUMMARY

At least one embodiment of the present disclosure is a microfluidicdispenser device for delivering inhalable substances that will enable atleast some of the limitations described above to be overcome or at leastmitigated.

According to the present disclosure, a microfluidic dispenser device fordelivering inhalable substances is provided.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a better understanding of the disclosure, some embodiments thereofwill now be described, purely by way of non-limiting example and withreference to the attached drawings, wherein:

FIG. 1 is a perspective view of a microfluidic dispenser device ofinhalable substances according to an embodiment of the presentdisclosure;

FIG. 2 is a perspective view of the microfluidic delivery device of FIG.1 , sectioned along the plane II-II of FIG. 1 ;

FIG. 3 is a perspective view of a microfluidic cartridge used in themicrofluidic delivery device of FIG. 1 ;

FIG. 4A is a side view of the microfluidic cartridge of FIG. 3 ,sectioned along the plane Iv-Iv of FIG. 3 ;

FIG. 4B is a side view of a microfluidic cartridge in accordance with adifferent embodiment of the present disclosure;

FIG. 5 is a perspective view of a component of the microfluidiccartridge of FIG. 3 ;

FIG. 6 is an exploded perspective view of the component of FIG. 5 ;

FIG. 7 is an enlarged perspective view of a portion of the component ofFIG. 5 , with parts removed for clarity;

FIG. 8 is a top plan view of an enlarged detail of the component of FIG.5 ;

FIG. 9 is a perspective view of the detail of FIG. 8 , sectioned alongthe plane IX-IX of FIG. 8 ;

FIG. 10 is a perspective view of a detail of a component of amicrofluidic cartridge that can be used in a microfluidic deliverydevice according to a different embodiment of the disclosure;

FIG. 11 is a perspective view of a detail of a component of amicrofluidic cartridge that can be used in a microfluidic deliverydevice according to a further embodiment of the disclosure;

FIG. 12 is a perspective view of a detail of a component of amicrofluidic cartridge that can be used in a microfluidic deliverydevice according to a further embodiment of the disclosure;

FIGS. 13A-13E illustrate operation of the component of FIG. 5 ;

FIG. 14 is a perspective cross-sectional view of a component of amicrofluidic cartridge that can be used in a microfluidic deliverydevice according to a further embodiment of the disclosure;

FIG. 15 is a top plan view of an enlarged detail of the component ofFIG. 14 ; and

FIG. 16 is a schematic lateral sectional view of a microfluidic deliverydevice according to a further embodiment of the disclosure.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2 , number 1 designates as a whole amicrofluidic dispenser device for delivering inhalable substances, whichin the embodiment illustrated is an electronic cigarette. Themicrofluidic delivery device 1 comprises a casing 2, housed within whichare a driving device 3, a battery 4, and a disposable microfluidiccartridge 5.

In greater detail, the casing 2 comprises an elongated tubular body 6made of polymeric and/or metal material, and includes a control housing7 and a cartridge housing 8. In one embodiment, the control housing 7defines a substantially axial blind cavity 7A, which is open at a firstend 2 a of the casing 2 and may be closed, for example, with anappropriately designed lid (not illustrated). The driving device 3 maybe welded on a support 10, for example a PCB (printed circuit board)that may be inserted in the cavity 7A in the control housing 7 togetherwith the battery 4.

The cartridge housing 8 encloses a chamber 8A set between the controlhousing 7 and a second end 2 b of the casing 2 and accessible through ahatch 11 for insertion and removal of the cartridges 5. The chamber 8Ain the cartridge housing 8 communicates with the outside through inletholes 13 and a mouthpiece 14 for release of the inhalable substance.More precisely, the inlet holes 13 and the mouthpiece 14 are arranged sothat suction through the mouthpiece 14 will draw air into the chamber 8Athrough the inlet holes 13, passage of the air through the chamber 8A,and subsequent release through the mouthpiece 14.

Electrical connection lines 15 are embedded in the casing 2 and extendbetween the cavity 7A and the chamber 8A for electrically coupling thedriving device 3 and the microfluidic cartridge 5 that is located in thechamber 8A.

FIGS. 3 and 4A illustrate an example of microfluidic cartridge 5, whichcomprises a tank 17, containing a liquid L that includes a substance tobe delivered, and a plurality of nebulizers 18 controlled by the drivingdevice 3. The nebulizers 18 are bonded to an outer face of a lid 5 a ofthe microfluidic cartridge 5, defined, for example, by a PCB andprovided with through channels 5 b for fluidic coupling of thenebulizers 18 to the tank 17. In the example of FIGS. 3 and 4A, inparticular, the microfluidic cartridge 5 comprises five nebulizers 18arranged in criss-cross fashion. The number and arrangement of thenebulizers 18 may, however, vary according to design preferences. In oneembodiment, even just one nebulizer 18 may be present.

In an alternative embodiment, to which FIG. 4B refers, the microfluidiccartridge 5 comprises a plurality of tanks, for example three tanks 17a-17 c, separated from each other and containing respective liquidsLa-Lc with respective distinct substances to be delivered. Each tank 17a-17 c is fluidly coupled with a respective nebulizer 18 or group ofnebulizers 18, distinct from nebulizers 18 or groups of nebulizers 18 ofthe other tanks. In this way, it is possible to deliver severalsubstances at the same time with controlled doses of each. The numberand size of the tanks, as well as the type and number of substances tobe delivered, may be selected according to project preferences.

FIGS. 5 and 6 show in greater detail one of the nebulizers 18. It isunderstood that the other nebulizers 18 have the same structure as theone illustrated. In other embodiments, however, the nebulizers coulddiffer as regards some details, such as the number and distribution ofthe ejection nozzles (described in greater depth hereinafter).

As may be appreciated more fully from the exploded view of FIG. 6 , thenebulizer 18 comprises a substrate 20, covered by an insulating layer21, a chamber layer 23, which extends over the insulating layer 21, anda nozzle plate 25 bonded to the chamber layer 23. The substrate 20, theinsulating layer 21, and the chamber layer 23 may, for example, be made,respectively, of semiconductor material, silicon oxide or siliconnitride, and a polymeric material, such as dry film. The nozzle plate 25may be made of the same material that forms the chamber layer 23 or ofsemiconductor material.

Supply passages 26 fluidically coupled to the tank 17 are providedthrough the substrate 20, the insulating layer 21, and the chamber layer23. In one embodiment, the supply passages 26 are circular andconcentric and define annular frame regions 27 comprising respectiveportions of the substrate 20, of the insulating layer 21, and of thechamber layer 23, which are also concentric. In the embodimentillustrated in FIGS. 5 and 6 , in particular, two outer supply passages26 define two frame regions 27 and separate them from the rest of thesubstrate 20. The innermost supply passage 26 is arranged at the center.Bridges 28 connect the frame regions 27 to one another and the outermostframe region 27 to the substrate 20.

It is, however, understood that the shape and number of the supplypassages (and consequently of the substrate portions adjacent to theopenings) may be freely defined according to the design preferences. Byway of non-limiting example, the supply passages could have a generallypolygonal or else rectilinear shape and be parallel to one another.

Chambers 30 are formed in the chamber layer 23 along the supply passages26, as illustrated also in FIG. 7 . In the embodiment illustrated, thechambers 30 are aligned along the inner and outer edges of the supplypassages 26 and are evenly distributed. Moreover, the chambers 30 arefluidically coupled to the supply passages 26 through respectivemicrofluidic channels 31 and are delimited by the insulating layer 21and, on the side opposite to the substrate 20, by the nozzle plate 25.

FIGS. 8 and 9 illustrate in greater detail one of the chambers 30. Inthe non-limiting example illustrated, all the chambers 30 have the sameshape, structure, and size.

The chamber 30 has a parallelepipedal shape with an approximatelyrectangular base and is delimited laterally by walls 30 a that define alateral surface of the chamber 30 itself.

The chamber 30 is provided with nozzles 32 formed in the nozzle plate 25in positions corresponding to respective corners of the chamber 30, sothat portions of the surfaces of the walls 30 a extend through the basearea of the nozzles 32. The access to the nozzles 32 from the chamber 30is hence partially obstructed, and the section of passage is a fractionof the base area of the nozzles 32. In the example illustrated, inparticular, the area of the section of passage is approximately onequarter of the base area of the nozzles 32. In an alternative embodiment(not illustrated), both the chambers and the nozzles are provided in thechamber layer. More precisely, the chambers are formed on a first faceof the chamber layer facing the substrate and occupy a portion of thethickness of the chamber layer itself. The nozzles extend for theremaining portion of the thickness of the chamber layer, between therespective chambers and a second face of the chamber layer opposite tothe first face.

The shape of the chamber 30 and the arrangement of the nozzles 32 arenot to be considered binding, but may be provided according to designpreferences. Alternative examples, which are in any case non-limiting,of the chamber 30 and of the nozzles 32 are illustrated in FIGS. 10-12(rectangular chamber 30 with niches 30 b at the vertices and nozzles 32partially overlapping the niches 30 b, FIG. 10 ; chamber 30 that isstar-shaped, with nozzles 32 in positions corresponding to the points ofthe star shape, FIG. 11 ; triangular chamber 30, with nozzles 32 at thevertices, FIG. 12 ).

A heater 33 (FIG. 8 ) is provided within the insulating layer 21 in aposition corresponding to the chamber 30, and forms an actuator. Theheater 33 may be made (by way of non-limiting example) ofpolycrystalline silicon, Al, Pt, TiN, TiAlN, TaSiN, TiW. A portion ofthe insulating layer 21, having a thickness such as to enable thermalcoupling with the chamber 30, coats a face of the heater 33 that facesthe chamber 30. Consequently, the heater 33 is separated from thechamber 30 and there is no direct contact between the heater 33 and theliquid present in the chamber 30. In one embodiment (not illustrated),the heater may be coated with a thin layer of an insulating andchemically inert material different from the material that forms theinsulating layer 21 so as to obtain in any case thermal coupling withthe chamber 30 and separation from the liquid L contained in the chamber30. The heater 33 is controlled by the driving device 3, to which theheater 33 is connected through the electrical connection lines 15 (FIGS.1 and 2), illustrated only schematically in FIG. 8 . The heater 33 mayhave an area of approximately 40×40 μm² and generate an energy of, forexample, 3.5 μJ, and is able to reach a maximum temperature of 450° C.in 2 μs.

Operation of the nebulizer 18 is illustrated schematically in FIGS.13A-13E. The liquid L reaches the chamber 30 from the tank 17, passingthrough the supply passages 26 and the microfluidic channels 31. Theheater 33 is activated by the driving device 3 for some microsecondsuntil it reaches a programmed temperature, for example 450° C. In thisway, a layer of the liquid L of the thickness of some micrometers israpidly heated, whereas the temperature of the rest of the liquid Lpresent in the chamber 30 does not vary appreciably, owing to the delayin conduction of heat. The pressure in the layer of liquid L adjacent tothe heater 33 increases to a high level, for example approximately 5atm, to form a vapor bubble 35 (FIG. 13B), which disappears after a fewmicroseconds, for example 10-15 μs. The pressure thus generated pushes adrop D of liquid 18 through the nozzles 32, as illustrated in FIGS.13C-13D, and then the liquid L present in the chamber 30 returns to theinitial condition (FIG. 13E).

The shape of the nozzles 32 and the area of the section of passage(which is determined by partial overlapping of the nozzles 32 and of thewalls 30 a of the chamber 30) are selected in such a way that the dropsreleased have a desired diameter. Advantageously, the use of nozzlesstaggered with respect to the walls of the chambers enables reduction ofthe area of the sections of passage between the chambers and the nozzlesand makes it possible to obtain drops having a very small diameter, aslittle as 1 μm, corresponding to a volume of approximately 0.0045 pl,without having to resort to sublithographic processing techniques.

The structure of the nebulizers 18, which can draw advantage from theprecision of semiconductor manufacturing techniques, enables anextremely accurate control over the amount of nebulized liquid and, inother words, over the dosage of the substance to be inhaled that isreleased. Moreover, release is carried out without heating significantlythe entire volume of liquid L present in a chamber 30. As has beendiscussed, in fact, it is sufficient to bring to a high temperature arather thin layer of liquid L to create a bubble and, consequently,release of a drop. In addition to preventing contamination of the liquidby direct contact with the heater 33, the nebulizers 18 preventexcessive heating from causing reactions that might alter substancespresent in the liquid L.

The number and arrangement of the chambers 30 and the number andarrangement of the nozzles 32 of each chamber 30 may be selected so asto create a uniform cloud of drops, which is desirable for favoringinhalation of the substances present in the liquid L. This is allowed bythe freedom of design offered by the semiconductor manufacturingtechniques.

In particular, in the microfluidic delivery device 1 the homogeneity ofthe cloud of drops favors mixing with the air that is drawn in throughthe inlet holes 13 and released through the mouthpiece 14.

FIGS. 14 and 15 illustrate an alternative example of arrangement of thenozzles 32. In this case, each chamber 30 is provided with five nozzles32, one of which is aligned to the center of the heater 33.

According to a further embodiment (illustrated in FIG. 16 ), amicrofluidic delivery device 100, in particular an inhaler for medicinalsubstances, comprises a casing 102, housed within which are a drivingdevice 103, a battery 104, and a disposable microfluidic cartridge 105.The driving device 103 and the battery 104 are located in a controlhousing 107, whereas the microfluidic cartridge 105 is located in acartridge housing 108. The microfluidic cartridge 105 may be made inaccordance with of the examples already described previously andcontains a liquid L′ in which at least one active principle is dissolvedin a controlled concentration.

A control pushbutton 109 enables activation of the driving device 103and causes release of a controlled amount of liquid L′ and,consequently, of an equally controlled dosage of active principle.Release is obtained through a mouthpiece 114 integrated in the casing102. In the example illustrated, no air-inlet holes are provided, andrelease of the amount of liquid L′ is carried out without pre-mixingwith a flow of air.

Finally, it is evident that modifications and variations may be made tothe microfluidic dispenser device described herein, without therebydeparting from the scope of the present disclosure.

The various embodiments described above can be combined to providefurther embodiments. These and other changes can be made to theembodiments in light of the above-detailed description. In general, inthe following claims, the terms used should not be construed to limitthe claims to the specific embodiments disclosed in the specificationand the claims, but should be construed to include all possibleembodiments along with the full scope of equivalents to which suchclaims are entitled. Accordingly, the claims are not limited by thedisclosure.

1. A nebulizer, comprising: a substrate including a surface; a heater atthe surface of the substrate; an insulating layer on the surface of thesubstrate and overlapping the heater at the surface of the substrate; achamber layer on the insulating layer, the chamber layer including: achamber that is aligned with and overlaps the heater, the chamberincluding: a central region aligned with the heater; a plurality ofperipheral regions that are around the central region; a nozzle plate onthe chamber layer, the nozzle plate including: a plurality of nozzlesthat extend through the nozzle plate to the chamber layer, each one ofthe plurality of nozzles overlaps a corresponding peripheral region ofthe plurality of peripheral regions.
 2. The nebulizer of claim 1,wherein the plurality of peripheral regions are at corners of thechamber.
 3. The nebulizer of claim 2, wherein the chamber has arectangular shape.
 4. The nebulizer of claim 2, wherein the chamber hasa triangular shape.
 5. The nebulizer of claim 2, wherein the chamber hasa star shape.
 6. The nebulizer of claim 1, wherein the plurality ofperipheral regions are a plurality of niches that extend from thecentral region.
 7. The nebulizer of claim 6, wherein the plurality ofniches are at corners of the central region of the chamber.
 8. Thenebulizer of claim 1, wherein the heater is one of a plurality ofheaters.
 9. The nebulizer of claim 1, wherein the heater chamber is oneof a plurality of heater chambers.
 10. The nebulizer of claim 1, whereinthe heater is fully overlapped by the chamber.
 11. The nebulizer ofclaim 1, wherein the heater is within the central region of the chamber.12. A microfluidic cartridge, comprising: a tank; a nebulizer in fluidcommunication with the tank, the nebulizer including: a substrate; aheater on the substrate; an insulating layer on the substrate andoverlapping the heater; a chamber layer on the insulating layer, thechamber layer including: a chamber that overlaps the heater, the chamberincluding: a central region aligned with the heater; a plurality ofperipheral regions that are around the central region; a nozzle plate onthe chamber layer, the nozzle plate including: a plurality of nozzlesthat overlap the plurality of peripheral regions.
 13. The microfluidiccartridge of claim 12, further comprising a lid on the tank, the lidincluding a channel extending through the lid and in fluidiccommunication with the nebulizer.
 14. The microfluidic cartridge ofclaim 12, wherein the nebulizer one of a plurality of nebulizers influid communication with the tank.
 15. The microfluidic cartridge ofclaim 14, wherein: the tank further includes a plurality of walls and atank cavity, the plurality of walls separate the tank cavity into aplurality of sub-tank cavities; and each nebulizer of the plurality ofnebulizers is in fluid communication with a corresponding a respectivesub-tank cavity of the plurality of sub-tank cavities.
 16. Amicrofluidic dispenser device, comprising: a casing; a driving circuitwithin the casing; a microfluidic cartridge within the casing, themicrofluidic cartridge including: a tank including a tank cavity; a lidon the tank, the lid including a channel that extends through the lidand is in fluid communication with the tank cavity; a nebulizer on thelid, the nebulizer in fluid communication with the tank cavity throughthe channel, the nebulizer including: a substrate including a surface; aheater at the surface of the substrate; an insulating layer on thesurface of the substrate and overlapping the heater at the surface ofthe substrate; a chamber layer on the insulating layer, the chamberlayer including a chamber that is aligned with and overlaps the heater;a nozzle plate on the chamber layer, the nozzle plate including aplurality of nozzles that extend through the nozzle plate to the chamberin the chamber layer.
 17. The microfluidic dispenser device of claim 16,wherein the chamber includes: a central region aligned with the heater;and a plurality of peripheral regions that are present around thecentral region.
 18. The microfluidic dispenser device of claim 17,wherein each one of the plurality of nozzles overlaps a correspondingperipheral region of the plurality of peripheral regions.
 19. Themicrofluidic dispenser device of claim 17, wherein the plurality ofperipheral regions are corners of the chamber.
 20. The microfluidicdispenser device of claim 17, wherein the plurality of peripheralregions are niches at corners of the central region.